president obama is out with his plan on gun control. the most sweeping in generations. as the nra uses the president's own daughters in an attack ad. as both sides harden for battle, we'll hear from both sides here tonight. >>> american hostages taken in a deadly terrorist attack. it's part of the world's newest war and we're there tonight. >>> is it safe for pregnant women to get the flu vaccine? there's news on that front tonight. plus other health news about the risk of migraines. >>> and making a difference. with a lesson in generosity. returning a little joy to some kids who lost so much. "nightly news" begins now. >>> from nbc news world headquarters in new york, this is "nbc nightly news" with brian williams. >>> good evening. it just might have changed everything. it's been a month now since 20 innocent school children were